The present invention relates to a molding device for molding various types of products in a cavity.
A conventional molding device as shown in FIG. 12 has been proposed. The molding device comprises a fixed mold 113 and a mold-holding member 115. The fixed mold 113 is detachably mounted to a mold-holding member 112 that is fixed to a bed 111. The mold-holding member 115 is mounted so as to reciprocate along guide rails 114 in the front and rear direction (left and right direction as viewed in FIG. 12) with respect to the mold-holding member 112. A movable mold 116 is detachably mounted to the mold-holding member 115. An injection mechanism 117 is arranged at the right side of the bed 111. Molten metal such as aluminum is fed via the injection mechanism 117 into a cavity that is defined by the fixed mold 113 and the movable mold 116 that are closed to mold a product. The injection mechanism 117 comprises a sleeve 118. The sleeve 118 includes a storing chamber 119 for molten metal that extends through the mold-holding member 112 to be connected to the fixed mold 113. An injection opening 120 for molten metal is formed at an outer edge of the sleeve 118. An injection rod 121 is inserted in the storing chamber 119 and is reciprocated by a cylinder 122.
In the above molding device, molten metal is injected into the storing chamber 119 from the injection opening 120 while the movable mold 116 is closed relative to the fixed mold 113. Then, the injection rod 121 is moved forward by the cylinder 122 so that the molten metal in the storing chamber 119 is pressed into the cavity. However, when the amount of the molten metal stored in the storing chamber 119 is excessive, an excess amount of the molten metal leaks to the outside through the die faces of the molds 113, 116, which can spoil the appearance of the product. To eliminate the problem, the amount of molten metal injected into the storing chamber 119 must be accurately calculated in advance. In this case, however, the efficiency of the molding operation is reduced.